what voltage is your alternator giving you?

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About 6 months ago I changed the stock alternator (180k) with a Denso reman on my 01 LX. Before the stock alternator went bad it would run up to 14.2, never dropped much below 13.7. Now it tops out at 13.9 and I see it as low as 13.3. After replacing the alternator I cleaned the battery terminals, replaced ground wires, had the battery tested, all sorts of stuff to try to get the charge back up with no success. It bothered me at first, but it runs fine so I've stopped worrying about it
 
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About 6 months ago I changed the stock alternator (180k) with a Denso reman on my 01 LX. Before the stock alternator went bad it would run up to 14.2, never dropped much below 13.7. Now it tops out at 13.9 and I see it as low as 13.3. After replacing the alternator I cleaned the battery terminals, replaced ground wires, had the battery tested, all sorts of stuff to try to get the charge back up with no success. It bothered me at first, but it runs fine so I've stopped worrying about it
yep, sometimes I find myself worrying about little changes in the numbers when I change over something. As long as your battery holds at or over 12.6v, have cold crank, charges whilst running with accessories and not discharging below 12.6v, generally you are ok.
Preferably over 13v and under 16v. If you ever run on solar you are simply happy if over 12.7v on a cloudy day.
I think regular full float and desulphate reconditioning is what makes the life of the battery last. I no longer fully rely on any alternator to fully maintain my batteries, hands down.
This is the same century marine 6 year old battery after a ctek recondition next day after reconditioning. The price of this battery certainly compares most favourably to a premium price optima yellow. However manufacturing companies tend to change hands more rapidly now, so 6-10 years is a long time in a ultra competitive manufacturers world. Of late I have heard bad reports of century.
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yep, sometimes I find myself worrying about little changes in the numbers when I change over something. As long as your battery holds at or over 12.6v, have cold crank, charges whilst running with accessories and not discharging below 12.6v, generally you are ok.
Preferably over 13v and under 16v. If you ever run on solar you are simply happy if over 12.7v on a cloudy day.
I think regular full float and desulphate reconditioning is what makes the life of the battery last. I no longer fully rely on any alternator to fully maintain my batteries, hands down.
This is the same century marine 6 year old battery after a ctek recondition next day after reconditioning. The price of this battery certainly compares most favourably to a premium price optima yellow. However manufacturing companies tend to change hands more rapidly now, so 6-10 years is a long time in a ultra competitive manufacturers world. Of late I have heard bad reports of century.
View attachment 3092596
take note slightly lower internal resistance which is good, the reconditioning slightly cooks and cleans the sulphur off the plates from my understanding. Be hard to expect any alternator to always do this.
 
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take note slightly lower internal resistance which is good, the reconditioning slightly cooks and cleans the sulphur off the plates from my understanding. Be hard to expect any alternator to always do this.
And here is a known bad battery, same age as the century, sold and priced as a premium which is bs. I hate when they use nylon string as the handle as the string rots and the battery becomes a bugger to remove from the engine bay, bad design. No sign of battery swelling, which is a dead give away that the battery is dead, the sulphur has grown on the plates and swells enough to expand the plastic case.

Admittedly not many manufacturers are going to warranty for 6 years, but I am a demanding bastard and expect the best from a reasonable price! Take note even though it is holding top end charge over 12.6v the cold crank is cactus and the internal resistance is much higher. I'll try a recondition and post just for interest, I know it is buggered.
Another note to take is never to store a battery where it is subject to moisture such as concrete slab or earth, apparently encourages the sulphur to build. Store it on something dry, rubber or timber. Sorry for the hijack, my kids get sick of my sermons.
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13-14V is a great range when you're running a lead acid battery. If you switch to AGM batteries (or LeFePO4?) they really want to see a higher charge rate. A bunch of us have swapped out the small 7.5A fuse in the engine bay fuse/breaker box and switch over to a diode that allows the alternator to charge a bit higher. I now routinely see 14.5-14.9V when running. Seems fine so far, and I haven't ready anybody else having issues, as long as you are running AGM batteries.
What diode did you use? Pic please? Good stuff.
 
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And here is a known bad battery, same age as the century, sold and priced as a premium which is bs. I hate when they use nylon string as the handle as the string rots and the battery becomes a bugger to remove from the engine bay, bad design. No sign of battery swelling, which is a dead give away that the battery is dead, the sulphur has grown on the plates and swells enough to expand the plastic case.

Admittedly not many manufacturers are going to warranty for 6 years, but I am a demanding bastard and expect the best from a reasonable price! Take note even though it is holding top end charge over 12.6v the cold crank is cactus and the internal resistance is much higher. I'll try a recondition and post just for interest, I know it is buggered.
Another note to take is never to store a battery where it is subject to moisture such as concrete slab or earth, apparently encourages the sulphur to build. Store it on something dry, rubber or timber. Sorry for the hijack, my kids get sick of my sermons.
View attachment 3092631
View attachment 3092647
after ctek recondition cycle it was too high a voltage for the tester to work something like 15v, I had to drain it with a light globe to about 13v. Cold crank is still cactus and resistance a bit higher. Top end of charge is plenty, so even if you measure the top end of voltage you do not really know how healthy your cold crank is.
Bottom line is, even if your alternator charges at a good voltage, regular reconditioning cycles of up to 15.5v, as the ctek does, is required to keep your battery for as long as possible. (imo!)
1661074903875.png
 

e9999

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well, I learned something today. Had to look it up. Never heard before. So now I know what "cactus" means down under. Didn't know you had any, btw. But thanks for the incentive!

On a perhaps related note, I personally would take those values of "measured" CCA with quite a bit of skepticism, as they are likely a wild extrapolation for this kind of meter. And, yes, it does seem like battery voltage is no clear indicator of good amps capacity. Anyway, this is not related to the alternator.
 
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well, I learned something today. Had to look it up. Never heard before. So now I know what "cactus" means down under. Didn't know you had any, btw. But thanks for the incentive!

On a perhaps related note, I personally would take those values of "measured" CCA with quite a bit of skepticism, as they are likely a wild extrapolation for this kind of meter. And, yes, it does seem like battery voltage is no clear indicator of good amps capacity. Anyway, this is not related to the alternator.
yep, I wouldn't say it is accurate, but the cactus one...certainly reads as low cca and it does not crank. The century one cranks but has less gusto . Have survived without the tester for awhile before, there are few things one really needs.
 

e9999

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Today, started with a fresh new, I think fully-charged, battery.

Right after start, at idle (700rpm), no A/C, in N, was 14.3V.
After 1.5 miles, 14.0V same conditions
After 7 miles, 13.6 V same conditions.
After that, no change.

with A/C and high fan on: - 0.1V same conditions
brake lights on: -0.05V same condns

regulator is doing a great job: I see hardly any difference between driving at 1000 rpm and 3500 rpm, maybe + 0.05V at the latter. Nice.
 
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Today, started with a fresh new, I think fully-charged, battery.

Right after start, at idle (700rpm), no A/C, in N, was 14.3V.
After 1.5 miles, 14.0V same conditions
After 7 miles, 13.6 V same conditions.
After that, no change.

with A/C and high fan on: - 0.1V same conditions
brake lights on: -0.05V same condns

regulator is doing a great job: I see hardly any difference between driving at 1000 rpm and 3500 rpm, maybe + 0.05V at the latter. Nice.
Excellent! Your a/c draws very little, amazingly so. I still get the impression that to ensure that sulphur does not grow on the plates it needs to have periods of over 14v at least, whilst 13.6v is ideal float.

You are right about the test meter being inaccurate, it measured the new on sale starter battery as a very low cca, but it cranks quite happily.
I also think measuring internal resistance is a good gauge whether your battery has sulphur build up.

We do have native succulents related to cactii such as the coastal 'pigface' which is a bit of bush tucker, usually very bland food. A feral weed prickly pear cactus was an introduced pest.

I thought you guys would have used 'cactus' as something 'kaput' too. I know you have cactii as I saw them on road runner and coyote. Now, that is a certain fact.
I met a German who was amused we use 'heaps' as describing ample..
 

e9999

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well, it's not obvious that the A/C only draws the equivalent of 0.1V drop, cuz the regulator is likely compensating for it to some extent, but maybe not perfectly because it is limited at what it can do at idle, no idea.

I keep on hoping I will see an anvil falling out of the sky someday in the desert, cuz I'd love to have one, but nothing so far....
"Heaps" is used in the US too.
 
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Today, started with a fresh new, I think fully-charged, battery.

Right after start, at idle (700rpm), no A/C, in N, was 14.3V.
After 1.5 miles, 14.0V same conditions
After 7 miles, 13.6 V same conditions.
After that, no change.

with A/C and high fan on: - 0.1V same conditions
brake lights on: -0.05V same condns

regulator is doing a great job: I see hardly any difference between driving at 1000 rpm and 3500 rpm, maybe + 0.05V at the latter. Nice.
Best I can say is I have identical voltages / symptoms. I only recently started monitoring this stuff just out of curiosity but I don't think there is any reason to be concerned here.
 
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So, I have in the past seen that the alternator ('03 OEM) on my earlier batteries was giving something like 14.4V right after startup, gradually going down to 13.9 V or so after a while of driving (with a dedicated voltmeter, not the dash one). This is just an impression from memory, not real tests. Those numbers seem fine, 14.4 is the standard bulk charging for FLA and it makes sense that it would go down when the battery is fully charged. OK.

However, after some possible electrical issues, I just replaced the battery with a new one which I assume to be in excellent condition and since paying attention to it, I saw that that the voltages seem noticeably lower. For instance, at idle in N without A/C (650-700 rpm) I get now about 13.6V, with A/C and fan on high it's more like 13.5V. When driving after a while, even at fairly high rpm for me (3K), it is around 13.7 , and I don't think it goes quite as high as 14.4V after startup now.
I'm happy to attribute that to the fact that the battery is new and really fully-charged, but I'm curious if there may be something else going on, so I gotta ask:

What voltages are you seeing at idle? Do you know what it is supposed to be per specs?
Mine is similar to you. the voltage floating around 13.3-13.6V during driving. starting with 13.8V or so. Mine battery is toyota OEM. I am guessing that voltage is depending on the regulation circuit based on battery. I am curious about if I change to AMG battery what voltage I can get.
 

awesomeissquid

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Quick question for the group. Last night I was driving back home with some stop and go in the middle of the 12 mile trip. At one stop I looked at my scangauge and noticed the voltage was down at 12.2-12.4V on idle. Once I started moving it went back up to 13.3ishV. Should I be concerned and do some more testing here? The alternator is pretty new (<2yrs).
 
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Quick question for the group. Last night I was driving back home with some stop and go in the middle of the 12 mile trip. At one stop I looked at my scangauge and noticed the voltage was down at 12.2-12.4V on idle. Once I started moving it went back up to 13.3ishV. Should I be concerned and do some more testing here? The alternator is pretty new (<2yrs).
My thought is the voltage should be regulated and should not be moving with engine speed. And if that voltage is less than 13.5 I'd consider something being wrong. Just my take on charging.
 

JunkCrzr89

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Quick question for the group. Last night I was driving back home with some stop and go in the middle of the 12 mile trip. At one stop I looked at my scangauge and noticed the voltage was down at 12.2-12.4V on idle. Once I started moving it went back up to 13.3ishV. Should I be concerned and do some more testing here? The alternator is pretty new (<2yrs).
Yes, that’s below spec.
 

e9999

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yup, 12.3V seems too low if connected to an alternator, even at idle and with headlights on, I would think. That's pretty much what I would expect of a decently charged battery with headlights on and no alternator at all. The alternator is clearly not completely dead since it went back up at higher rpm, so probably the regulator?
 

awesomeissquid

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Guess I will see if it’s still in warranty. Might be time to swap to the 4-pin higher amp alternator I have sitting on the shelf.
 

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maybe check the voltage again under more controlled conditions like in your driveway at idle in Park or N with no load on? And if still that low, see at what rpm it kicks in? [Long shot: belt is not slipping, right?]
 

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